Old standby: Milkweed, just beginning to bloom at the outdoor gardens at the Butterfly Pavilion in Westminster, is a host plant for monarch butterflies. (Cyrus McCrimmon, The Denver Post)

Nothing thrills a gardener like the sight of butterflies flitting through the garden. The brightly colored, winged pollinators transform a mere backyard into an animated celebration.

What attracts these special creatures? Butterfly bushes, coneflowers, sunflowers and other showy plants that provide a perch and plenty of nectar. Then, of course, there are host plants, such as milkweed and rabbitbrush, which provide egg-laying sites and food for the caterpillars that eventually become butterflies. And a butterfly garden has to have both types of plants.

Each year, growers and garden centers introduce still more plant varieties to tempt gardeners and the 250 butterfly species that call Colorado home.

Old standby: In the pavilion's outdoor garden, a chokecherry shrub was covered with the white blooms that swallowtails use for egg-laying. (Cyrus McCrimmon, The Denver Post)

One new 2014 introduction is echibeckia — a cross between echinacea (coneflower) and rudbeckia (black-eyed Susan). This nectar-producing perennial combines the hardiness and disease resistance of echinacea with the beauty and fast growth of rudbeckia. A long bloomer, echibeckia pumps out 3-inch-wide flowers for two to three months. You might not find it at garden centers yet, but keep an eye out.

The cone zone

Among local plant experts, coneflowers rank high for ability to lure butterflies.

"That Cleopatra coneflower ... has that big, wide-open flower that they really like," she notes. A dwarf variety, it yields blooms up to 3½ inches wide with an orange cone and startling yellow petals accompanied by rich, green foliage.

"Cheyenne Spirit" is another variety to try, she says. "It's kind of a mixture of warm-toned colors." A 2013 All-America Selections (AAS) winner, Cheyenne Spirit generates an explosion of flowers in a mix of yellows, oranges, creams and whites.

Old standbys: Penstemons are notorious draws for pollinators of many types, including sphinx moths. (Cyrus McCrimmon, The Denver Post)

For gardeners who prefer rosy colors in their echinaceas, Ginger Jennings, perennials supervisor at Tagawa Gardens in Centennial, recommends "PowWow Wild Berry." PowWow remains a standout since its introduction in 2010 as an AAS winner.

New plants: "Cheyenne Spirit" echinacea gives gardens not just butterfly food, but a blaze of oranges, pinks and yellows. (Provided by All-America Selections)

As for butterfly bushes — Buddleia species — the tiny, 2½-feet-tall varieties garner mixed reviews from Amy Yarger, horticulture director at the Butterfly Pavilion in Westminster.

"I think the dwarf butterfly bushes, in some ways, make it possible for folks to grow them in smaller gardens," she says. (The classic butterfly-bush varieties can grow tall enough to tower over a garden gate.) Butterflies, she explains, often avoid flitting too close to the ground because of low-lying predators.

Among the 2014 butterfly-bush introductions, "InSpired Violet" impresses butterflies and hummingbirds alike with its fragrant purple blossoms that hover anywhere from 4 to 10 feet high.

Perhaps the most versatile butterfly shrub introduced in recent years, however, is baby blue rabbitbrush, a dwarf version of the native rabbitbrush seen all over the West, glowing with bright yellow blossoms in late summer/fall. The shrub was a 2011 Plant Select pick.

"Rabbitbrush is a trooper," Yarger points out. "It'll bloom all the way through Halloween, and it's got bright gold color that butterflies love. So it's a great nectar plant. But it also is a host, an egg-laying plant, for checkerspot butterfly."

Lockheed says object part of 'sensor technology' testing that ended ThursdayWhat the heck is that thing? It's fair to assume that question was on the minds of many people who traveled along Colo. 128 south of Boulder this week if they happened to catch a glimpse of what appeared to be a large, silver projectile perched alongside the highway and pointed north toward town.